COP8SA-DM National Semiconductor, COP8SA-DM Datasheet - Page 26

• Manufacturer Part Number: COP8SA-DM
• Description: MODULE DEBUGGING FOR COP8SA
• Manufacturer: National Semiconductor

Specifications of COP8SA-DM

• Module/board Type: Debugger Module
• For Use With/related Products: Cop 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *COP8SA-DM

However, the accumulator-based machine requires operands to be moved into the
accumulator before instructions are executed. Which takes longer in the end? It depends
on how much faster an accumulator-based machine can execute an instruction than a
register-based machine.
Trade-off memory efficiency—An accumulator-based machine will generally have
shorter opcodes than a register-based machine.
Interrupts
Interrupt is an event which causes the microcontroller to stop executing code in its
normal sequence and instead respond to the occurrence of the event. The microcontroller
performs the following steps when an interrupt occurs:
1-14
MICROCONTROLLER BASICS
1. Stops execution of the "next" instruction.
2. Disables additional interrupts.
3. Saves current status of the microcontroller.
4. Jumps to a special interrupt handling routine.
5. Returns from the special interrupt handling routine.
6. Restores state of the microcontroller
7. Enables interrupts
8. Executes the "next" instruction.
Figure 1-6 Adding Two Numbers Using Register Based Machine
Addent #1
Addent #2
Register 1
Register 2
Register 3
A
ALU